Magnetic viscous fluid and mechanical device

A magnetic viscous fluid comprising:

• a magnetic particle,
• at least one selected from ester base synthetic oil, ether base synthetic oil, and alkylnaphthalene having an alkyl group with 10 to 20 carbons,
• an inorganic cation exchanger with a siloxane bond, and
• silicone oil,
• wherein the ester base synthetic oil is at least one selected from polyol ester and dibasic acid ester,
• the ether base synthetic oil is polyalkylene glycols,
• a mixing ratio of the inorganic cation exchanger with a siloxane bond and the silicone oil is in a range of 2:8 to 8:2 by mass, and
• the inorganic cation exchanger with a siloxane bond is at least one selected from zeolite, bentonite, montmorillonite, bidelite, nontronite, hectorite, stevensite and kaolinite.